This invention relates generally to floating boat lifts, and more particularly to a floating boat lift which utilizes water-fillable upper pontoons to affect loading and unloading of a boat to and from the device.
Other devices are known to applicant which utilize pontoons in conjunction with a boat lift device. Applicant is the inventor of U.S. Pat. No. 4,955,308 which is directed to a boat lift having two spaced pontoons and cable-actuated cradle which travels arcuately on support arms.
Another patented device is disclosed in U.S. Pat. No. 4,018,179 to Rutter which teaches a pontoon system having two pairs of pontoons, one pair of which is fillable with water for submersion and elevation of a central cradle portion of this device.
Applicant is also aware of the following additional U.S. patents which are directed to pontoons with fillable chambers and having a fixed interrelationship between components:
______________________________________ 1,486,257 Muller 1,486,258 Muller 2,894,472 Foster 3,976,022 Lapeyre 4,267,788 Blanco 2,834,311 Engstrand 4,273,061 Lundberg 4,510,877 Bloxham 4,615,289 Bloxham ______________________________________
The present invention discloses a floating boat lift which includes a unique arrangement of spaced upper pontoons held above, and made vertically movable with respect to, a lower pontoon base. The upper pontoons are fillable with water so as to facilitate loading and unloading of the boat atop a rigid frame connected between the upper pontoons.